Ninety-eight days into his Prime Ministership John Howard stood in front of a crowd of thousands with the outline of a flak jacket visible through his brown blazer. It was the first time a prime minister had worn a bulletproof vest in Australia's history. As soon as he stepped onto the stage to address the thousands of gun enthusiasts in the small country town of Sale on June 16, 1996, Howard knew the body armour was a mistake.

But it perhaps reflected the nervousness of the country. It spoke to the intensity of a debate enraging a nation and echoed the tragedy which had just unfolded.

Forty-eight days after Howard stepped into office, Martin Bryant murdered 20 people in less than two minutes at the Port Arthur Historic Site's Broad Arrow Café with a military-style semi-automatic. Another 15 people were dead by the time his deadly rampage was over. The 28-year-old had killed 35 people and injured 23. It was the worst mass killing by a lone gunman in Australia and the third worst massacre by a single person in history.

The gun he first used was an AR15. The weapon is in the company designation of the M16, which can be equipped to hold 20 to 30-round magazines and has a rate of fire more than 700 rounds per minute. U.S. troops used the weapon in the Vietnam War.

Then 28, Bryant had no criminal record or diagnosed mental illness. But even if he did, it wouldn't have mattered.

At that time, in many states -- including Tasmania – there were no restrictions on a civilian with a mental illness applying for a gun licence, which in many cases was then valid for life. Minors in many states could also purchase guns including semi-automatics, which in many states, again, did not require registration.

Head of Emergency at the Royal Hobart Hospital, Dr Bryan Walpole, saw the extent of the damage inflicted by Bryant's semi-automatic. Three days after the massacre, Walpole stood on the steps of St David's Cathedral at the memorial.

He had just seen Walter Mikac, who lost his three girls -- two daughters and wife – at the hands of Bryant. As Mikac walked past, distraught, Walpole broke down. Howard who was walking out too, stopped, and embraced him, a defeated look on his face.

It was the most human moment in Howard's prime ministership, which Leigh Winburn, a photographer at The Mercury captured. But it was important for another reason.

"Someone said to me once, 'do you think at that point the Prime Minister thought we must do something about gun legislation, we must do something about the buyback? Was that part of it?' And I believe it was," Winburn told The Huffington Post Australia from his house in Hobart, 100 kilometres north of Port Arthur.

On May 10, Howard banned all automatic and semi-automatic weapons in the country. It was the most drastic gun control measure in the nation's history. Every state and territory agreed on the reforms at an emergency meeting of The Australasian Police Ministers' Council.

As the casualties were rushed into the Royal Hobart Hospital on April 28, Dr Stephen Wilkinson, who was Head of Surgery, also saw the damage of Bryant's bullets. They left scars not only on the victims, but emotionally wounded the community.

"It's become an indelible part of Tasmanian history and Port Arthur has sort of taken a double meaning now. Its original history was bad enough, but now it sort of has another scar on top of it," Wilkinson told HuffPost Australia from his office in Hobart.

"I thought it was a good thing for the Prime Minister to do; to immediately see the lesson to come out of Port Arthur... and to so quickly put policy in place. It was a sensible and courageous thing to do."

May 1, 1996: At the memorial of the massacre, former Prime Minister John Howard consoles Dr Bryan Walpole at St David's Cathedral in Hobart.

All self-loading and pump action shot guns, self-loading rim-fire and centre-fire rifles were banned. Australians showing a "genuine need" would still be able to own low-powered self-loading .22s and pump-action shotguns, but the gun licencing protocols were strengthened, gun safety courses introduced and all guns required registration. And for those getting a gun licence after the legislation was introduced, they would not be able to purchase a gun for the first 28 days in what the Federal Government described as a "cooling period".

In the space of a year the Government bought back more than 600,000 now-illegal firearms at market value in a national buyback scheme funded by a temporary hike in the Medicare levy.

"It was one of those challenges that come unexpectedly but if you're elected to be the Prime Minister of a country you must be willing to respond," former Prime Minister John Howard told The Huffington Post Australia.

"Nothing can ever prepare you for a disaster or tragedy of this magnitude but I was determined that I would use the authority of a newly elected government, and a government with a very large majority to do something that would have lasting benefit for the country."

And while Australia has not experienced another massacre since the buyback, many sports shooters were in uproar over the legislation, believing it demonised gun owners. "Hitler Howard" signs were held up at rallies, including the rally in Sale, where the AFP received such a serious threat the Prime Minister's Chief Of Staff begged him to wear the flak jacket.

But the blame wasn't exclusive to the Prime Minister.

The board of the Port Arthur Historic Site dealt with an onslaught of abuse. Chair of the board, Michael Mazengarb, often woke to the phone ringing in the middle of the night with strangers on the other end.

"The gun laws weren't acceptable to everyone and someone had to be blamed for it."

Still to this day there is stern opposition to Howard's gun control legislation.

As recently as November, Liberal Democratic Senator David Leyonhjelm appeared in a National Rifle Association of America video claiming Australia is "a nation of victims" because of the tough laws, which he claims have made no difference to gun violence, despite gun homicides more than halving since 1990.

Leyonhjelm negotiated with the Federal Government to lift a ban on the Adler lever-action shotgun, using his vote against Labor's migration policy amendments as a bargaining chip.

The Shooters and Fishers Party has constantly pushed back on the laws, and Tasmania's own Shooters and Fishers Party is aiming to take seats in the next election and be recognised as a political party in the state. The party intends to continue its campaign towards loosening gun control laws.

Video by Emily Verdouw

Peter Crosswell laughs about being the last of the 'Great White Hunters'. He was also in The Broad Arrow Café when Bryant went on the violent rampage. Crosswell jumped in front of the two women he was with that day, and all survived.

"John Howard wrote to me personally, and I believe he wrote to most people down in Port Arthur who survived it," Crosswell told HuffPost Australia.

"He wrote about changing the gun laws and [asked] if I would participate, and try to bring weight to bear in the right places to make sure it happened."

Crosswell said Tasmania "lost its innocence" on April 28, 1996.

"Tasmania certainly hasn’t been the same since. It's changed the way we think," he said.

"And I think through changing the gun laws, they actually changed the way Australians think. I feel that we, as a country, really made a much safer place."

Now 7,305 days have passed since the Port Arthur massacre. Not one massacre has taken place since.

And while April 28, 2016 marks 20 years since one of the most harrowing tragedies in our nation's modern history, it serves as a profound lesson for young Australians.

"We've got a few generations who have been born since Port Arthur," Wilkinson said.

"I think that's probably one of the things that anniversaries can do; they can remind us of history so that we don't repeat the same mistakes."

*Editor's note: This story has been amended to provide more information about the gunman's weapon.